SIMULTANEOUS DELIVERY OF ELECTRON-BEAM THERAPY AND ULTRASOUND HYPERTHERMIA USING SCANNING REFLECTORS - A FEASIBILITY STUDY
SIMULTANEOUS DELIVERY OF ELECTRON-BEAM THERAPY AND ULTRASOUND HYPERTHERMIA USING SCANNING REFLECTORS - A FEASIBILITY STUDY
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DOI：
10.1016/0360-3016(94)00469-2
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发表时间：
1995-02-15
影响因子：
7
通讯作者：
MYERSON, RJ
中科院分区：
文献类型：
--
作者：
MOROS, EG;STRAUBE, WL;MYERSON, RJ
目的：同时提供外部电子束辐射和浅表热疗使用扫描超声反射器阵列系统（SURAS）的可行性进行了实验研究和demonstration.Methods和材料：一个新的系统使用扫描反射器分布的声能从平面超声阵列的表面上的目标体积。外部光子/电子束可以通过扫描反射器照射与热疗同时递送。也就是说，该系统使得声波和辐射束能够从相同的方向进入目标体积。反射器由空气等效材料制成，以实现最大的声反射和最小的辐射衰减。声学上，空气反射器进行了比较，黄铜反射器（假设理想）的反射率和镜面质量使用几个单一的换能器频率范围从0.68到4.8 MHz，相对反射率确定从声功率测量使用力平衡技术。通过比较由空气反射器反射的声压场与由黄铜反射器反射的声压场来评估镜面质量。此外，声压场产生的SURAS原型为两个不同的阵列（2.24和4.5 MHz）进行了测量，调查持有的分布变化作为一个函数的距离分开的阵列和扫描反射器。所有的压力场都是在脱气水槽中用水听器测量的。最后，为了确定空气反射器对电子剂量分布的影响，这些都是使用薄膜测量后，通过20 MeV的电子束通过SURAS的水等效的固体幻影。这些测量进行了连续扫描的反射器在整个电子束和在休息内的电子beam.Results：使用单超声换能器进行的测量表明，空气反射器的功率反射率为87-96%的黄铜;和光滑的表面，从空气反射器的反射镜面的黄铜反射器。两个不同阵列的SURAS的声压场测量结果表明，50%的压力振幅等值线分布均匀，在整个阵列的投影表面积为不同的距离分离的阵列和反射器。最后，胶片剂量测定表明，无论是扫描情况下还是静止情况下，SURAS的空气反射器都不影响电子剂量分布。这表明，所制造的反射器在高能电离辐射方面基本上与水相当。测得的等剂量线也表明，构建的SURAS原型将允许提供足够的辐射（90%等剂量线）的深度为2.0 cm。结论：结果表明，SURAS设计有可能提供高温大浅表肿瘤，白色允许同时照射20兆电子伏的电子束的辐射剂量输送没有不良影响。
Purpose: The feasibility of simultaneously delivering external electron beam radiation and superficial hyperthermia using a scanning ultrasound reflector-array system (SURAS) was experimentally investigated and demonstrated.Methods and Materials: A new system uses a scanning reflector to distribute the acoustic energy from a planar ultrasound array over the surface of the target volume. External photon/electron beams can be concurrently delivered with hyperthermia by irradiating through the scanning reflectors. That is, this system enables the acoustic waves and the radiation beams to enter the target volume from the same direction. Reflectors were constructed of air-equivalent materials for maximum acoustic reflection and minimum radiation attenuation. Acoustically, the air reflectors were compared to brass reflectors (assumed ideal) for reflectivity and specular quality using several single transducers ranging in frequency from 0.68 to 4.8 MHz, The relative reflectivity was determined from acoustic power measurements using a force-balance technique. The specular quality was assessed by comparing the acoustic pressure fields reflected by air reflectors with those reflected by brass reflectors. Also, acoustic pressure fields generated by a SURAS prototype for two different arrays (2.24 and 4.5 MHz) were measured to investigate held distribution variations as a function of the distance separating the array and the scanning reflector. All pressure fields were measured with a hydrophone in a degassed water tank. Finally, to determine the effect of the air reflectors on electron dose distributions, these were measured using film in a water-equivalent solid phantom after passage of a 20 MeV electron beam through the SURAS. These measurements were performed with the reflector scanning continuously across the electron beam and at rest within the electron beam.Results: The measurements performed using single ultrasound transducers showed that the air reflectors had power reflectivities of 87-96% that of brass; and that for smooth surfaces the reflections from air reflectors were as specular as those from brass reflectors. Acoustic pressure fields measurements of the SURAS for two different arrays showed that the 50% pressure amplitude contours were well-distributed across the projected surface area of the array for different distances separating the array and the reflector. Finally, film dosimetry showed that the electron dose distribution was not affected by the air reflector of the SURAS either for the scanning case or the stationary case. This indicates that the reflectors as made are basically water-equivalent in terms of high energy ionizing radiation. The measured isodoses also indicate that the constructed SURAS prototype would allow the delivery of adequate radiation (90% isodose) to a depth of 2.0 cm.Conclusions: The results presented show that the SURAS design has the potential to deliver hyperthermia to large superficial tumors, white allowing simultaneous irradiation with 20 MeV electron beams without adverse effects on the radiation dose delivery.